The present invention relates to a process for the removal of unnecessary resist material on an object such as semiconductor wafer and side wall protective film which has been deposited on the side wall of pattern during dry etching at a step of forming fine pattern during the preparation of semiconductors, circuits, various printed circuit boards, various masks, lead frames, etc.
In the process for the preparation of semiconductors, a resist pattern is formed, e.g., on a silicon wafer. With this resist pattern as a mask, the substrate is the subjected to injection of impurity ions, dry etching, etc. Unnecessary resist material is then removed normally by means of an asher (carbonization apparatus). In this manner, circuit elements or wiring are formed.
The foregoing dry etching is preferably carried out by side wall protection process to attain etching anisotropy. In some detail, this process involves the incorporation of a polymer-forming gas (e.g., halocarbon gas such as CCl4 and CF4) in an ionized etching gas for etching an object such as semiconductor substrate with a resist pattern as a mask, whereby a polymer protective layer is formed on the side wall of the pattern to prevent radicals from entering into the side wall of the pattern, making it possible to effect anisotropic etching free from side etching (see FIG. 4).
However, such a side wall protection process is disadvantageous in that the removal of resist material by an asher after etching cannot be accompanied by the removal of the foregoing side wall protective film and it is thus necessary to add a separate step of cleaning the side wall protective film after the preceding steps. Thus, the side wall protection process is liable to disadvantages in production process.
Under these circumstances, an object of the present invention is to collectively remove unnecessary resist material and side wall protective film after dry etching by side wall protection process, thereby simplifying the process for the preparation of semiconductors, etc.
The inventors made extensive studies of the foregoing object. As a result, it was found that the use of a process which comprises applying a pressure-sensitive adhesive sheet to an object which has been subjected to dry etching by side wall protection process, and then peeling the pressure-sensitive adhesive sheet of the object makes it possible to collectively remove resist material and side wall protective film therefrom. The present invention has thus been worked out.
The present invention concerns a process for the collective removal of resist material and side wall protective film which comprises removing unnecessary resist material left behind after dry etching by side wall protection process with a resist pattern present on an object as a mask and side wall protective film deposited on the side wall of pattern, said process comprising the steps of applying a sheet-like or tape-like pressure-sensitive adhesive sheet to the object, heating the pressure-sensitive adhesive sheet under pressure so that the pressure-sensitive adhesive comes in contact with up to the side wall of pattern, and then collectively peeling the pressure-sensitive adhesive sheet, the resist material and the side wall protective film off the object.